The present invention relates to a process for producing L-glutamic acid by fermentation, and more specifically to a process for producing L-glutamic acid by culturing an L-glutamic acid producing mutant microorganism belonging to the genus Corynebacterium or Brevibacterium in a nutrient medium and recovering the L-glutamic acid produced thereby. The microorganisms employed are mutants endowed with a resistance to .alpha.-naphthoquinoline, an antibiotic inhibiting energy metabolism or a precursor for ubiquinone biosynthesis.
L-glutamic acid is an important amino acid which is commercially useful as a food additive. Accordingly, it is an object of the present invention to provide an improved process for production of such amino acid on an industrial scale at low cost.
Heretofore, as processes for producing L-glutamic acid by fermentation, there have been known processes of using strains having a nutritional requirement for various compounds, strains having sensitivity to various chemicals, or various chemicals-resistant strains, belonging to the genus Corynebacterium or Brevibacterium.
The production yields of known processes are comparatively low from a commercial application standpoint. Thus, a need exists for a process for producing L-glutamic acid in higher yields at low cost.
As a result of various studies for obtaining strains having an increased L-glutamic acid productivity, it has been found that a strain capable of producing L-glutamic acid belonging to the genus Corynebacterium or Brevibacterium endowed with a resistance to .alpha.-naphthoquinoline, an antibiotic inhibiting energy metabolism or a precursor for ubiquinone biosynthesis has a remarkably improved ability to produce L-glutamic acid.